Sí, probablemente estemos... probablemente deberíamos

¡Hola Steven-W15!

The subjunctive is certainly one of the trickiest elements in Spanish!

The reason why the first phrase uses the subjunctive and the second uses the conditional is because they're expressing slightly different things.

In the first phrase, probablemente estemos is "(we) probably are," and the subjunctive is used because it is reflecting that there is some doubt or uncertainty.  

In the second phrase, probablemente deberíamos means "(we) probably should," and the conditional is used because it is expressing something that is more of a recommendation. It doesn't reflect the same doubt that is shown by the use of the subjunctive - it is more real, or concrete.

I hope that this was helpful!

Saludos,

Liss 

THE trickiest element. I could kind of "feel" this one but it's nice to get confirmation and a clear explanation.  ¡Gracias, Liss!
 

¡De nada, Steven-W15! :)